Assessment and modeling of contaminant transport at a burial site in Middelburg (Mpumalanga South Africa)

Abstract

Most present cemeteries were sited without any consideration of the potential risks they may have to the local environment and community. The metals used in coffin-making may gradually weaken into harmful contaminants. These harmful contaminants may mobilize into the groundwater and surrounding soils. According to the literature reviewed, there has been inadequate research carried out on the contamination of groundwater by metals from cemeteries. In light of the aforesaid, the research study aims to assess the mobility of metals from graves that may leach into and contaminate the surrounding soils and groundwater. This study was conducted at the Fontein Street Cemetery in Middelburg (Mpumalanga, South Africa), where 5 boreholes were drilled for the investigation of hydrogeological, geochemical and geological characteristics of the site. The boreholes were monitored for a period of six months, with water samples collected on a monthly basis. Moreover, a total of thirty-eights soil samples and fourty-three water samples were collected for XRD & XRF and ICP-MS analyses, respectively. The analysis of XRD and XRF indicated that the geology of the area is composed of Loskop Formation Sandstones and Dwyka Group Shales, this was also observed on the geological logs of the drilled boreholes. The unsaturated zone of the study site has high concentrations of Zn2+, Rb2+, Sr2+ and Zr2+ which appeared to have not leached into the groundwater. This was primarily because the unsaturated zone of the area is composed of clay-sand material of low porosity. Water results indicated high concentrations of Cl- and Ca2+ from one deep cemetery borehole and high concentrations of SO42- from the stream near the cemetery, the municipal water, shallow cemetery boreholes and the Athlone dam. A hydrocensus was conducted for a comparison of water qualities between on-site and off-site boreholes downgradient to the study area. Upon analysis of the results, no correlation was established between water qualities of on-site and off-site boreholes. High concentrations of SO42- from the stream, Athlone dam, shallow cemetery boreholes and the municipal water may have resulted from contamination of surface water by acid mine drainage from the surrounding mines within the B12D quaternary catchment. Nonetheless, soils below the grave area have high concentrations of metals than those away from the grave area. Accordingly, this proves that burial practices do indeed influence metal concentrations in cemetery soils, albeit it takes longer for them to reach deeper levels and eventually leach into the groundwater.